FIELD OF THE INVENTION
The present invention relates to the treatment of cocoa, and more particularly, to an improved method and system for dutching of cocoa for attaining a rich color, improved flavoring and other favorable parameters.
Heretofore, the process of dutching of cocoa has been a relatively long and expensive proposition. Basically, the same batch process wherein the cocoa is treated in large cooking vats has been used for at least 100 years without significant improvement. In most prior art processes, after roasting the beans and removing the husk or shell, the broken pieces of the beans, commonly referred to as the nibs, are crushed or ground to break the cells and form a smooth, creamy paste, known as chocolate liquor. Next the liquor is fed a hydraulic press whereby with the proper timing, temperature and moisture control and removal of a portion of the fat or cocoa butter, a press cake is formed. Typically, the press cake is next broken up and mixed with an alkalizing solution in the batch pressure cooker. The cooker then converts to a vacuum dryer to reduce the moisture content in the batch. The contents of the vat are then deposited in drums or other suitable containers for several days and allowed to cool. The cooled mass is then ground to a fine powder that can be used in devil's food cake, chocolate drinks, chocolate ice cream and chocolate cookies.
The standard batch process of the prior art suffers from several shortcomings. First, the conditions of treatment from batch to batch must be rigidly maintained in order to obtain proper moisture, pH, and low microbial flora content and uniformity of flavor and color. By the very nature of the non-continuous process, this has been found to be extermely difficult to do and requires the constant monitoring of people and machines. Secondly, the vat cooking and drying of the batch and the absence of significant mechanical working result in nonuniformity of heating of the cocoa so that parts are scorched and other parts are undercooked, giving a nonuniform product in terms of color and taste. The color obtained in the batch process is not as dark and rich in color with the same amount of alkali that is desired in many commercial products. In addition to requiring additional equipment and people to maintain the proper conditions, the large vats further financially burden the processor since the space required to house the equipment is substantial.
Problems of the prior art batch drying processes have resulted when previous attempts to depart from the above procedure have been made. First the danger of charring has arisen when the drying process has been attempted to be accelerated by employing a higher temperature. The prior processes have not included a necessary volume of working gas to distribute the heat to the end product efficiently and uniformly. The problem of case hardening of the individual cocoa solids is also a nemesis in the prior processes. This arises when the temperature of the product solid rises too rapidly thereby hardening the outer surface of the product. It is caused, in part at least, by not providing suitably small sized product solids, controlled heat, and large volume gas flow. Grinding and regrinding of the hardened solids thus becomes a trying necessity in an attempt to gain a satisfactory product.
In the past, the above overall "batch method" has been attempted to be replaced by a continuous method. Such attempts have, however, been unsuccessful and exemplary of those known in this art is shown by the U.S. Pat. to Walker No. 1,167,959. The failure of the continuous processes has keyed on the inability to find a way to successfully form the mixture of cocoa material and alkaline solution and cook the same and the failure to devise a method for efficiently drying and cooling the cocoa end product in a continuous manner.
A more recent process for preparing dutched cocoa may be found in U.S. Pat. No. 3,754,928, a patent issued on Aug. 28, 1973, or subsequent to the filing of applicant's parent application. This patent discloses a method for dutching cocoa by subjecting an aqueous alkaline solution of cocoa to frictional and compressive forces to rapidly raise its tempeature to 200-300.degree. F. within about 10 seconds and maintaining this temperature for about 45 to 75 seconds prior to cooling. The patent discloses that the frictional and compressive forces may be applied by extrusion of the mixture through a die. The mixture initially contains about 4 to 6 parts by weight of water and after drying contains about 4 parts by weight of water. However, this process requires high temperatures and careful control of temperatures and residence times in passing the mixture through the die as well as intense initial pressurization. Moreover, the low initial moisture content is detrimental to good working of the mixture because 4 to 6 parts of water saturated with alkali is an insufficient amount of liquid to wet out all particles of cocoa subject to frictional and compressive forces. The consequences of incomplete wetting is incomplete chemical reaction and unequal distribution of the alkali used. Therefore, because of this, poor control of production of varieties and intensities of color in the cocoa as well as in the finished product in which the cocoa is the result.
A second recently issued patent, U.S. Pat. No. 3,778,519, teaches that in the impregnation of cocoa seeds with alkali or water and eventual sterilization, requires that the moisture content be kept as low as possible because of subsequent difficulties in drying. The present invention provides a procedure where outstanding results are obtained using high initial moisture contents. Accordingly, the method of the present invention represents improvements in the art of dutching cocoa.